I just find it curious that your HE400 measurements are the only ones where the upper midrange is not visibly recessed. Not calling the compensation wrong, just saying it is definitely quite different from InnerFIdelity or [N/A].

Not a great idea IMO; I tried that a long time ago and all it did was compress the foam inside the earpad, rather than gently lifting the section of the earpad. Bad for comfort, and no benefit to the SQ.

Gotcha. I have no comfort issues with the stock earpads. Have a skinny head I guess.